Water treating apparatus



, April 8, 1958 J. P. LAwLoR WATER TREATING APPARATUS 2 Sheets-Sheet lFiled Aug. 23, 1955 April 8, 1958 J. P. LAwLoR WATER TREATING APPARATUS2 Sheets-Sheet 2 Filed Aug. 23, 1955 United Seres, Patent@ WATERTREATING APPARATUS Joseph Patrick Lawlor, Ames, Iowa, assignor toGeneral Filter Company, Ames, Iowa, a corporation of Iowa ApplicationAugust 23, 1955, Serial No. 530,090

9 claims. (cielo-197)j i u This invention relates to a water treatingapparatus, and more particularly to an apparatus' of the type which isknown in the water treating art as an upflow sludge clarifier. Theprincipal elements of such'an apparatus, as they have been previouslyknownfin the art, are illustrated by Spaulding Patent No. 2,021,672',`and byr Green Patent No. 2,368,354.

This application is a continuation-in-part ofmy copending applicationUnited States Serial Nonf 272,954, filed February 23, 1952, Vand nowPatent No. 2,7-2l",173. The subject matter that is now being claimed insaid application, however, differs substantially from the subject matterthat is being claimed in this application.

It is a general object of this invention to provide an upflow sludgeclarifier which provides -operating Vcharacteristics and advantageswhich distinguished itfrom previously known equipment within thisgeneral' classicatioh. The important features ofmy invention will becomemore apparent as the specification proceeds.

The accompanying drawings illustrate there embodiments of my invention,wherein Figure'l is a crosssectional view of an upfiow sludge clarifier,as is Fig. 2, and Fig. 3 is a partial detail view of elements which canbe substituted for the corresponding elements shown in the embodimentsof Figs. `l and12.

In studying the operation of upflow sludge clariers, I have found thatideally three distinct Izones are required within the clarifier. Thesezones are: (l) a fast mixing or reaction zone, (2) a slow mixing orflocculation zone, and (3) a clarification or `sedimentation zone.Heretofore, partitions have been employed in upllow sludge claritiers toprovide separate mixing and clarification zones, but to my knowledge noone has heretofore provided a slow mixing zone between the fast mixingzone and the clarification zone. It is not merely a matter of providingthree distinct zones, however, since the zones must interact in aparticular manner to achieve the desired results. In the fast mixingzone, the raw water should be thoroughly and rapidly intermixed with-thechemical reagents and the recirculated sludge. Asthe new precipitatebegins to form, and before thefloc particles have grown to a size thatthey are broken up by the violent agitation of the fast mixing zone, thewater being treated should be passed to the slow mixing zone. In theslow mixing zone, the water should be continually and gently mixed whilethe `particles of lloc-continue to enlarge in size and untilsubstantially all of the water contaminants have been precipitated. Thewater then should pass into the clarification' zone wherein thecirculatory movement is substantially eliminated.

In connection with the above discussion, it must be realized that themixing zone, the llocculation zone,` and the clarification zone must" bearranged in open communication with each other so thata continuous flowin either direction can take-place within the zones. This poses adifficult problem of 'equipment design. The desired agitationfinthetiocculationfzbne mustnot 'be' ob- 2,829,776 ,Pearse APL 8- .195??FCC- t Y 2V t the occulatedfmaterial wasI even occasionally driven intothe final `stagesof the clarification zone. the separation oftheocculated material from the water is'gprincipally effected-bypassing thewater upwardly through a suspended sludge` blanket in the lower portionof the clarification zoneyit is desirable to provide meansfori-removingrtheflarger, heavier particles of sludge from the lowerportion of the Asl-u'dge blanket. YAt the same time, itvis desirable tocirculate the smaller, lighter particles of sludge from the sludgeblanket into and through the fiocculation`zone.:;. y y I t Ihavediscovered that the design objectives whichhave justvbeen outlined'canbe achieved in ahighlyadvantageousl 4Trnannerlby employing a rotatingsludge-collecting pocket within. theflocculationf zone. IMbelievedthiselement-of my apparatus vto be entirely novel. Sludgecollecting pocketshave heretofore'been used in upflow sludgefrclarifiers, but as -fartasI, am aware allsuch pockets have been-stationary. Moreover; they havenot been4 definitely located within.` they flocculation zoneasdistinguishedy Afrom the mixingr and-clarification zones.y Inrwatertreating apparatus constructed in accordance wi'thfmy invention, therotating sludge pocket within the flocculatio'nzone has a unique action.ItV tends to maintain the integrity of a separate flocculation zonevbetween the-mixingzoneganlwthe clarification zone -by functioning as aspecial-'typeof mixing element. VItalso appears to exert a directin'gaction on the character of the sludge materialwhich circulates withinthe occulation zone and between the lower portion-ofthe clarificationzone and the occulation zone. As the sludge particles descend centrallywithin the tank from the lower portion of the clarification zoneintotheflocculation zone, there appears to-be a vdefiniteitendency forthe'particles tov be classified by the rotary motion of the pocket. Thelighter descending particlesare-.diverted lfrom the mouth of the pocketand areA circulatedrthroughY the flocculation zone, while the heavy;oversize 'sludge particles are collectedin the-pocket, and effectivelyremoved from the fiocculation zone.` Furtherdetails of operation willbecome apparent Iupon vreference to the specific embodiments shown inthe accompanying drawings.

vLooking 'first 'at the embodiment of Fig. `l, there is shown a tank 10having a partition means 11 therein providing an outer,peripherally-extending chamber '12 and an inner,Yupwardly-'enlargingchamber 13. Chambers-,12 and 1?are4 1in-open.communication beneath .partitioning meansv 11.u `Inlthe -illustrationgiven, tank 10 is circular and is formed of concrete. It can be ofother"shapes,.however, and may be fabricated from other materials suchas ste'el.V 'When tank 10 is circular, 'outer chamber 12 willi-be,annular, .while partitioning means 11 consist generally'of4 afrusto-conical wall. In any case, the horizontal .cross-sectional .areaof chamber 13 should increase progressively in an upward direction fromthevpassage between chambers 12 and 13. For

1 convenience of construction, partitioning means 11 will usually .beformed from `steel or other 'metal sheets.

A` centrally-positioned, vertically-extending lshaft 14 isV mounted'for.' rotation 'within inner' chamber 13,' appropriaterotationallbearingsl being provided at `15 and165 Azplurality of mixingarm-s 17 are mounted on the lower endof shaft 14 and arranged to extendoutwardly beneath partitioning means'll into outer chamber 12. In theillustration given, arms 17 consist of hollow pipes havinglaterallyrturned outer ends 18, but this constructainedatthe'expense-.of interfeingxwith the.` operation Also, since shaft 14. Aplurality of vertically-aligned batles 22 extend inwardly frompartitioning means 11 toward vessel 21 and upwardly to a level above theAtop of the vessel.

There is also provided means l:for removing material from vessel 21while it is 'rotating with shaft 14. In the illustration given, two suchmeans are provided, one

being for recirculation of sludge from vessel 21 to chamber 12, and theother being for discharging sludge from vessel 21 to waste. Therecirculation means consists of a pipe 23 within vessel 21 that providesan annular passage 24 around the lower end'of shaft 14. Annular passage24 is arranged to communicate with the inner ends of hollow arms 17,thereby permitting sludge to be drawn from within vessel 21 throughannular passage 24y and hollow arms 17, and then discharged intocharnber 12. This is accomplished by an aspirating or suction effectwhich is created by the motion of -thelaterally turned 'end portions 18of arms 17 `as described more fully and claimed in my ico-pendingapplication Serial No. 272,954, now Patent No. 2,721,173.

In addition, a sludge withdrawal pipe 25 extends into vessel 21 and isprovided with Ian inlet near the bottom thereof; The sludge ca-n he`periodically or continuously discharged from the 'lower portion ofvessel 21 through pipe 25 by means of the static pressure within thetank. Preferably, Yas shown, vessel `21 comprises a conical pocketmounted concentrically on shaft 14 with the mouth of the pocket facingupwardly.

Appropriate pipe means are provided for introducing the raw water intochamber 12. Inthe illustration given, this consists of a header 26 fromwhich the raw water is discharged into the upper portion of chamber 12through 'outwardly-extending pipes `27. If desired, the chemicaltreating agents can be introduced Atogether with the raw water, Vor theymay be introduced separately. For example, the chemical treating 'agentsmay be introduced into chamber 12 through a' pipe 28.

Means Vare, provided for vrotating shaft 14, which as shown in Fig. l,consistrofan electric motor 29 mounted adjacent the upper endof Shaft 14and arranged to drive the shaft. 'The apparatus'also includes a laundei30 for collection of the clarified water. 'In the .illustration given,the 'clarified water 'passes into the launder 30 through perforations 31in we ir wall 32., andthen ows outwardly through discharge pipe33. Forthe removal of excess sludge 'from the bottom of the tank, a sump 34 isprovided, -having asludge removal pipe 35 connected thereto. Also, ifdesired, outwardly extending baffles 36 can be provided'within outerchamber '12, being arranged -with lrespect to rotating arms 17 andpaddles 19 to promote'mixingand agitation `withinthe Aouter chamber. 1

In the 'operation of the-,embodiment of Fig. l, the raw water andtreating reagents are 4introduced'into 'the upper portion 'of outervchamber1'2,.whic=h functions ras the fast mixing or reaction z'one. -Avariety of chemical reagents can be used, as 'is well -knowninfthe art,'for the purpose `of reducing the alkalinity and eliminatiing theexcessive hardness ofthe water. The commonest .of these are perhapslime, alum, and lsoda ash. The 'specie chemicals employed, however, `donot form va part of the present invention. `Within the :zone provided byouter chamber 12, the Vraw w'ater r,andchemicals are rapidly-andthoroughly intermixed. V'Atnthesarne time, the process of precipitationis .accelerated by the :mixing of previously formed sludge with thewater, vthe sludge being recirculated from vessel 21 to chamber 12through the-hollow mixing arms 17. After the water has been thoroughlyAreacted with the chemicals and asludge, but before the new precipitatehas Vformed into `large flocks which can be broken up 'by the turbulentagitation within zone 12, the treated'fwater is passed `beneathpartitioning means 11 into the lower portion of 4inner chamber'13. Thelower portionof this chamber tup to v'thetop of vessel 21 `provides theslow mixing or occulation zone.`

The continual rotation of vessel 21 maintains the integrity of thiszone, and establishes a general swirling or rotary motion of the water.This permits the size of the new sludge particles to increase to a pointwhere the particles can be effectively removed from the water by passingit upwardly through a suspended sludge blanket which extends upwardlyfrom the level of the vessel 21 to a spaced but somewhat variabledistance from the top of tank 10. The swirling or rotary motion of thewater as it moves from the flocculation zone into the clarilication zoneis reduced' by the action of stilling baffles 22, and at the same timethe yupward velocity of the water is decreased due to the enlargingcross sectional area of the clarification zone. In the final stages ofthe clarification zone, near the top of tank 10, the velocity of thewater is very low, there is substantially no turbulence, and the wateris completely free of suspended sludge particles. The clarified water isthen withdrawn through launder 30.

It will be evident that the suspended sludge blanket acts as a filter,removing the newly formed sludge from the water as it passes upwardly.When the particles within the sludge blanket become heavier or largerthan can be suspended by the upward velocity of the water, and thisoccurs continuously, sludge particles will descend from the lowerportions of the sludge blanket into the flocculation zone. Most of thisoversized material will tend to descend centrally within the tank due tothe shielding action of conical vessel 21, which diverts the upwardlyrising currents away from the central arca of the tank. As thedescending material approaches the mouth of vessel 21, the rotary motionof the water in this arca will tend to classify the descending material,the lighter material moving outwardly with the rotary currents over th:top of vessel,21,and into the. occulation zone. The heavier materialwill thendescend into vessel 21, and either be recirculated to mixingzone l2, as previously described, or removed fromgthe vessel to waste.

The embodiment of Fig. 2 lis similar to that of Fig. l, and thereforecorresponding parts have been given the same numbers, except thatthe,numbers Vhave been primed. It will be understood, therefore, that theprevious description of the mechanical elements and the operation ofthese elements for the embodiment ofFig. l can be applied te theVembodiment of Fig. 2. f There is one difference, however, which Idesire to discuss.

It Vwill be noted that lthe stilling baffles 22, instead of beingimperforate -plates as inthe embodiment of Fig. l. are in the form ofperforated grids or expanded metal screens. This construction has adefinite advantage when the baffles are made to extend into theilocculation zone and to closely .approach the rotary vessel 2l. 'Therotary motion of the water within the flocculation zone will cause thewater andthe suspended sludge therein to be thrownagainst-thebaiiles.The perforated grid construction Y,shown-in Fig. 2 givesnssurance .thattheturbid water and sludge will not bethrown upwardly into theclarinettion zone, so as to yinterfere with the action o-f this zone. orprevent the withdrawal .of fully clarified water at the top .of thetank. The perforated grid construction also cooperates withthesrotatingvessel vto maintain theV desired `slowagitation within `the occulationzone, while at the same time preventing .the .swirling or rotary motionof the water from extending itself ,upwardly into the clarificationzone. .If desired, the portions of baflles 22 extending above themouthof pocket orvessel 2l. can be made imperforate whilethezlowerportions are perforated.

Theipartial detail view of Fig. 3 illustrates a modified form ofstillingV baffle, whichis designated generally by theLnumber 22",:andtherelationship ofthisbafe to a rotarysludgeLcollecting pocket 121".Baffie 22" is in the form'of agrill composedzof a-plurality ofvertically suspended rrods .37, which are .pivotally .connected jattheir upper zend to support bar .38. .Bar 38 is suspended by cables 39so that' its height in. relationto .pocket21",can

be adjusted. For certain installations, this constructionA might beadvantageously substituted for the stilling baffles and rotary sludgecollecting pocket arrangements described with respect to the embodimentsof Figs. 1 and 2. With larger units, it would permit adjustment of thestilling baiiies for controlling the location and extent of theocculation zone.

While in the foregoing specification this invention has been describedin relation to specific embodiments thereot` and many details Vhave beenset forth for the purpose of chamber in open communication with eachother beneath said partitioning means, a centrally-positioned,verticallyextending shaft mounted for rotation within said innerchamber, mixing arms mounted on said shaft and extending outwardlybeneath said partitioning means into said outer chamber, an open-toppedvessel mounted on said shaft in the lower portion of said inner chamberat a spaced distance from said partitioning means for rotation in unisonwith said shaft, and a plurality of verticallyaligned bafes extendinginwardly from said partitioning means toward said vessel and upwardly toa level above the top of said vessel.

2. The combination of claim 1 in which said vessel comprises a conicalpocket mounted concentrically on said shaft.

3. The combination of claim 1 in which at least the lower portions ofsaid baffles have openings therethrough for reducing the retardingaction of said baliies within the zone immediately adjacent saidrotatably-mounted vessel.

4. In a water treating apparatus, a tank having partitioning meanstherein providing an outer, peripherallyextending chamber and an inner,upwardly-enlarging chamber in open communication with each other beneathsaid partitioning means, a centrally-positioned, verticallyextendingshaft mounted for rotation within said inner chamber, mixing armsmounted on said shaft and extending outwardly beneath said partitioningmeans into said outer chamber, a conical pocket mounted concentricallyon said shaft above said arms and at a spaced distance inwardly fromsaid partitioning means, said pocket enlarging upwardly and having anopen mouth at a spaced distance above the lower end of said partitioningmeans,

means for removing material from said pocket when it is rotating withsaid shaft, and a plurality of verticallyaligned baffles extendinginwardly from said partitioning means toward said pocket and upwardly toa level above the top of said pocket said mixing arms carryingupwardlyextending mixing paddle means but only on the portion thereofoutwardly of said partition means, whereby there is provided a fastmixing Zone in said outer, peripherallyextending chamber and a slowmixing zone in the lower portion of said inner, upwardly-enlargingchamber.

5.V The combination of claim 4 in which at least the lower portion ofsaid baies which extends below the mouth of said pocket are in the formof perforated grids.

6. The combination of claim 4 in which said baies are composedprincipally of spaced-apart, vertically suspended rods.

7. The combination of claim 6 in which said rods are suspended from avertically-adjustable support.

8. In a water treating apparatus, a tank having a truste-conicalpartitioning means therein providing an outer, annular chamber and aninner chamber enlarging in cross sectional area in an upward direction,said chamber being in open communication beneath said partition, acentrally-positioned, vertically-extending shaft mounted for rotationwithin said inner chamber, hollow mixing arms mounted on said shaft andextending outwardly beneath said partitioning means into said outerchamber, a sludge-collecting pocket mounted `on said shaft within thelower portion of said inner chamber for rotation in unison with saidshaft, means providing a passage from within said pocket to within saidhollow arms, the outer end portions of said hollow arms being adapted todischarge sludge from said pocket into said outer chamber, a pluralityof vertically-aligned baffles extending inwardly from said partitiontoward said sludge-collecting pocket and upwardly to a level above thetop of said pocket, means for introducing raw water and chemicalsinto'said outer chamber, and means for withdrawing claried water fromthe upper portion of said inner chamber.

9. The combination of claim 6 in which said baes have perforated gridportions extending above and below the top of said pocket.

References Cited in the le of this patent UNTTED STATES PATENTS2,245,583 Green June 17, 1941 2,347,318 Gurney Apr. 25, 1944 2,673,181Hughes Mar. 23, 1954 2,721,173 Lawlor Oct. 18, 1955

